Anatomy of Flowering Plants Test - 50

A.Rhizodermis – the outermost layer of tubular living cells in dicot root.

B.Epidermis – the outermost layer of dicot root.

C. Hypodermis – it is absent in dicot root.

D.Exodermis – outermost layer with suberised cell wall.

So, the correct option is ‘Rhizodermis’.

In the internal structure monocot root, different regions from outer to inner are, epidermis, general cortex, endodermis, pericycle, vascular bundle, conjunctive tissue and medulla are present.

Secretory cavities formed by the disintegration of cells in a tissue are called lysigenous cavity. In monocot stems(maize), some of the protoxylem cells disintegrate and form into a lysigenous cavity. it is called protoxylem lacuna.

The ligno-suberised thickenings present on the radial and tangential walls of the endodermal cells are called Casparian strips or Casparian bands.

So, the correct option is ‘Suberin’.

A.Sunflower – Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

B.Pisum - Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

C.Maize – Ground tissue is undifferentiated.

D.Cucurbita - Ground tissue is differentiated into hypodermis, general cortex and endodermis, pericycle, medulla and medullary rays.

So, the correct option is ‘Maize’.

In the stele of dicot root, outer most part is the pericycle, and inner vascular bundles medulla, conjunctive tissue is present. Vascular bundles are radial with exarch xylem. Tetrarch stele is present, means stele with four xylem strands. Medulla is reduced due to extensive growth of xylem into the centre.

The inner most part of the cortex in root and dicot stem is endodermis. it is single layered. Cells are barrel shaped and thick walled. On the radial walls and tangential walls, ligno suberised thickenings are present. These are called Casparian thickenings. Some of the endodermal cells lack casparian bands. These are called passage cells. These cells are present opposite to the protoxylem cells. Endodermis acts as check point, and prevents the outflow of water and minerals from the stele into cortex, and also acts as a barrier in the inflow of water and mineral from cortex and stele either by active methods or passive methods.

So, the correct option is ‘Suberin’

Shull studied inbreeding depression in maize. Miller and Letham extracted a hormone from its seeds of the plant maize. Maize is a monocotyledon.The root anatomy shows, outer epidermis, middle cortes and central stele with pericycle, medulla, vascular bundles, conjunctive tissue. In the anatomy of the stem. outer epidermis,inner small ring of sclerenchymatous hypodermis and large ground tissue in which vascular bundles are scatteredly arranged. In this, general cortex, endodermis, pericycle, medulla, medullary rays are absent. The leaf anatomy shows, upper and lower epidermises, middle mesophyll with spongy parenchyma and vascular bundles.

A.True - In dicot root, pericycle is parenchymatous both in young as well as mature states, but in monocot roots, pericycle is parenchymatous in young state, sclerenchymatous in mature state.